Bool tool leaves parts after slicing
Use Boolean Modifier (instead Bool Tool) with Exact solver, plus enable Self - intersection, because those &quot;red&quot; teeth are overlapping.

... or in edit mode select all and with pivot point set to Individual Origins scale all teeth a bit so they don't overlap.

... and enable under Data Properties &gt; Normals &gt; Auto Smooth if you want to fix shading around edges.
Also I would highly suggest to use Un-Subdivide operator in edit mode, your topology is too dense. You can use Iterations up to 4 for shark and 4-6 for teeth. Result is pretty much the same with much lighter file and faster calculation. To make it smooth add Subdivision Modifier only for Shark before Boolean.